Treatment of polyene compounds



I Patented Nov. 12 1946 UNITED STATES. PATENT OFFICE TREATMENT OF POLYENE COMPOUNDS Anderson W. Ralston, Chicago, and Otto Turinsky, Palatine,- 111., assignors to Armour and Company, Chicago, 111., a corporation of Illinois No Drawing. Application January 22, 1942,

V Serial No. 427,832

This invention relates to processes of treating polyene organic compounds and it more specifically relates to the treatment of unconjugated polyene organic material, such as fats and fatty acids having a plurality of double bonds with amine hydroiodides, whereby the unconjugated polyene materials are converted to conjugated polyene products or to products having. improved drying or resinifying qualities.

It has hitherto been-recognized that the chemical properties of unsaturated organic compounds double bonds. It is believed that in linolenic 6 Claims. (01. zoo-405.6)

about this change can be materially reduced by the use of high boiling organic solvents and strong alkalies.

ducting the reaction in aqueous solution at elevated temperatures and pressures. However, any such process which employs alkali has inherent disadvantages; In order to conduct this process it is necessary that the fats or fatty acids be converted to soaps. These soaps must then be acidified in order to obtain the transformed fatty acids. Where one desires to conjugate :an oil a number of steps are, therefore, necessary in order acid the double bonds are in the 910, 12-13 and 15-16 position while in eleostearic acid they occupy the 9-10, 1112 and 1314 positions. Thus in eleostearic acid the doublebonds are conjugated. When linseed oil is used as a paint vehicle the paint dries quite differently than it would if eleostearic acid. were used. Eleostearic acid is the chief fatty acid constituent present in tung oil glycerldes. Tung oil body-dries whereas linseed oil film-dries. Body-drying is much preferred and is believed to result from the fact that eleostearic acid is conjugated.

Therefore, it is highly desirable that ways be developed by means of which unconjugated highly unsaturated compounds can be converted to conjugated, unsaturated compounds and thus gain the advantages inherent in conjugated systems.

The fact that the relative position of double bonds in an alkyl chain can be changed by treatment with strong alkalies has been known for some time. In Biochem. J. 31, 138 (1937) Moore reported that treatment of fats and fatty acids with alcoholic potassium hydroxide brings about a shift in the relative positionof double bonds in an alkyl group and that this shift is towards a conjugated configuration. Recently Kass and Burr, J. Am. Chem. Soc. 61, 3292 (1939) have shown that the time necessary bring to produce desired results by these processes. It is necessary to first saponify the fat and then to treat, the soaps with strong caustic in order to bring about conjugation, acidify the resulting soaps, purify the fatty acids-and finally reesterify them with glycerine.

It would be extremely desirable to develop a process whereby the unconjugated fatty :acids or fats could be treated-directly without the necessity of saponification or other chemical change.

Such a process would be much easier to conduct on a commercial scale and would have a number of apparent advantages over the alkali processes for bringing about this transformation....Even before the introduction of the alkali methods various investigators have sought to find compounds which would produce the desired isomerization directly. For example, the Schreiber patent No. 1,896,467 lists a number of compounds including sulfuric acid, ferrous iodide, chlorine, oxygen, etc., for this purpose; but none of these compounds have proved effective or have come into commercial use.

We have now discovered a class of compounds I which catalytically improve to a very marked degree the drying or resinifying properties of unconjugated systems. This improvement involves a change of-the unconjugated unsaturated system'to a conjugated unsaturated system but we cannot definitely state that all the improvement in'drying properties is explained by this transformation. The substances which we use to bring about this transformation are used in relatively small amounts at elevated temperatures which shows that they function as true catalysts.

The class of compounds we use can be generally described as amine hydroiodides. These compounds have the general formula NX1.HI, in which'formula X can be hydrogen, or a hyd o-' carbon radical, and the hydrocarbon radical may be saturated or unsaturated or may be substituted or unsubstituted. Ammonium iodide is a Other investigators have found that the alkali process may be improved by con-,

completely unsubstituted member of this series.

Other examples of such compounds are'the primary' amine hydroiodides, represented by the mixture is heated to produce a shifting of th double bonds whereby a conjugated. compound is formed. In general we can treat any organic polyene compound which contains doublebonds in u'nconjugated relation. Of-thenatural oils, linseed .oil and soya bean oil are particularly susceptible to this treatment, and castor oil and fish oil are also markedly improved bythe treatment. Other oils such as cottonseed oil, peanut oil, corh oil and other oils not ordinarily regarded as drying oils. can also be treated by this procedure and their drying characteristics substantially improved. Instead of treating the oils directly, we can hydrolyze the oils to obtain the natural mixtures of fatty acids and then subject the mixture to .the'treatment for producing con-.

' jugation. The conjugated mixtures thus prepared may suitably be reacted with a polyhydric alcohol and a dibasic acid to form alkyd resins, or may be re-esterified with glycerol-or the higher alcohols such as pentaerythritol or dipentaerythritol to form synthetic g'lycerides having improved drying characteristics. I

Particularly in connection with the oils which are not normally classed as drying oils, such as cottonseed oil, corn oil, peanut oil, soya bean oil, etc., we find that especially good results can be obtained by first subjecting the acid mixture obtained from such an oil to fractional distillation and then subjecting a relatively low'boiling volatile fraction so obtained and containing a higher proportion .of the polyene acids, to the catalytic treatment described above.

. Another procedure'includes first subjecting the acids obtained through hydrolysis of natural oils to solvent extraction whereby there is produced a portion which contains unsaturated acids in greater proportion than in the original acid mixture, and then subjecting this portion to catalytic treatment as before described or, additional benefits may be obtained by first fractionally distllling the acid mixture, treating the fraction so obtained by solvent extraction, and then catalytically treating the resulting product using an amine hydroiodide as'the catalyst.

Though our improved process finds its greatest advantage in connection with those oils or natural mixtures of fatty acids which are classed as unconjugated oils or acids, the process can also be used to advantage in connection with oils and acids normally classed as conjugated by containing appreciable amounts of unconjugated com- 4 Example 1 h Ten parts by weight of linoleic acid containing approximately 25% of oleic acid were admixed with 0.02 part by weight of ammonium iodide. Most of the ammonium iodide did not dissolve in the acid,.but solution of the catalyst in the fat or fatty acid is not essential. This mixture was then heated. After about four minutes heating, the temperature rose to about 200 C. and three minutes later thetemperatur'e was about 300 C. The mixture was then cooled and the treated oil analyzed for increase in diene value. Under these conditions the diene value rose from 2, that of the original linoleic acid. to 35.4, that of the final reaction product. The refractive index rose from 'mo=1.4692 to n2o=1.4767 and the iodine value dropped from 160 to 115. These results indicate marked conjugation in the final product.-

Example 2 Ten parts by weight of the linoleic acid of Example 1 were mixed with 0.05 part by weight of' dimethylaniline hydroiodide and heated for a period of seven minutes in a nitrogen atmosphere.

and was 310 C. at the end of seven minutes. The fatty acid was then allowed to cool and the final diene value was 37.3. The iodine number so of the product was 119.5 and the refractive index Example 3,

Ten parts by weight of the linoleic acid of I Example 1 were mixed with 0.024 part by weight Example 4 Thirty parts by weight of linoleic acid containing twenty-five percent of oleic acid was heated for twelve minutes with: 0.06 part of di-nbutylamine hydroiodide. The temperature was 170 C. after four minutes and 295 C. after ten minutes, and the final temperature was 300 C. The initial and final constants were as follows: refractive index; initial mo=1.4693, final nzo=l.4776; iodine value, initial 160, final 119; diene value, initial 2.0, final 33.1. It is evident that appreciable conjugation has been brought about by this treatment.

Twenty-six parts by weight of the treated acids were mixed with 2.7 parts of glycerine and 0.28 part of catalyst (p-toluene sulfonic acid). The mixture was placed in around bottom container. swept out with nitrogen and heated for five hours so at 125 C. A stream of nitrogen was passed through the container during the heating period.

in order to avoid oxidation. An equal volume of solvent (Skelly Solve F) wasthen added, and the acids removed by washing the oil layer with'l0% 65 ethyl alcohol containing a small amount of KOH. After the acids were removed the product was dried with anhydrous sodium sulfate-and the solvent removed under vacuum. The iodine value .of the resulting triglyceride was 106, and the diene value 32.2.

A film of the triglyc and observed. w This filmdried completely after thirty-six hours, and showed no tackiness after this time. The dried oil film was quite opaque which is characteristic of deep drying. a

During the heating the temperature rose rapidly eride was placed on glass Example 5 Twelve parts by weight of refined and bleached Example 6 One-hundred and ten parts by weight of dehydrated castor oil fatty acids were'heated with 0.06 part of diethylaniline hydroiodide in nitrogen atmosphere for thirty-nine minutes The maximum temperature was 300 C.

There was no increase in viscosity during this treatment. The following initial and final values were obtained; diene value, initial 19, final 28; iodine value, initial 151, final 123; refractive index, initial nzo=1.4723, final, 1220:1479. These results show that there has been considerable increase in conjugation brought about by this treatment and also that the treatment can be applied with benefit to mixtures of acids which are already partially conjugated.

Example 7 lower boiling temperature amounting to aboutv 30% by volume of the original acid mixture; another volatile fraction of higher boiling point amounted to about 50% by volume of the original acids; and a third product which contained a large Proportion of non-volatile material was about 20% of the original acid mixture. The second fraction, which was about 50% of the original acids, contained a high percentage of unsaturated acids having two or more double bonds, including clupanodonic acid which is supposed to have five double bonds.

Approximately five hundred parts of the second fraction obtained as explained above were mixed with 0.3 part of dimethylaniline hydroiodide andthe mixture heated in a nitrogen atmosphere for twenty minutes at 280 C. The

initial diene value of this second fraction was 2.0, and the diene value after the treatment was found'to be 31.3.

Two hundred and fifty parts of the treated acids were esterified with twenty-six parts of glycerine using 2.7 parts of p-toluene-sulfonic acid employed as catalyst. The mixture was placed in a container swept with nitrogen and heated for five hours at 125 C. The free acids were removed and the product dried as described under Example 4. A sample of this dried glyceride was placed on a glass plate and it was found that the film dried completely after thirty hours giving a frosted tone characteristic of our treated glycerides.

I Example 8 Acids obtained from soybean oil were fractionally distilled as set forth in Example I, and a prpduct obtained which by volume of the original acids and which contained a substantial percentage of linoleic acid.

This product was treated with dimethylaniline hydroiodide as desribed in the previous exampies, and the treated acids were esterifled with glycerol. A comparison of the drying properties of the treated product with those of the original oil showed a very marked improvement, and drying was of the deep type characteristic of conjugatcd oils.

Emample 9 Ten parts by weight of the linoleic acid of Example 1 were mixed with 0.02 part by weight of triethanolamine hydroiodide. v The mixture was heated for fourteen minutes and the final temp rature was 300 C. The product was then cooled and the diene and iodine values determined. The initial diene value was 2 and the final 25. Theiodine value dropped from 160 to The amount of catalyst required is small. The amounts given in the foregoing examples have been found to give good results but still lesser quantities may be employed. More than the quantities stated can, of course, be used but this is wasteful and serves no useful purpose. If desired the catalyst may he removed from the final oil by any of the usual refining methods, but in general we prefer not to remove it since its presence is usually not harmful.

During the heating and cooling it is of special invention may be practiced'without this feature. We can operate at various times and temper-- atures. One of the characteristics of our invention is that conjugation is imparted quite rapidly, and this is a definite commercial advantage. Our oils and fatty acids can be heated for longer periods of time, if, for example, it is desired to impart bodied characteristics to the oil rather than conclude the heat treatment after conjugation alone has been imparted to the oil or fatty acid. That is to say, conjugated, unsaturated fatty acids and glycerides thicken when heated for somewhat longer periods of time than we have indicated in our examples. can, of course, impart conjugation to "the unsaturated compound during a relatively short period and continue the heating for a longer period of time, up to two or three hours, if we wish to body the oil or fatty acid. Such thickened oils have much higher viscosity than the simple conjugated fluid oils, and this may be the result of polymerization of the conjugated material pres-' ent. Therefore, we do not wish our invention to be limited to any particular time of heating. Those skilled in the art will understand different oils may require different heating periods and that the oil or fatty acid is to be heated until aptemperatures of the order of C. or below and under certain conditions this has been found to amounted to about 50% Therefore, we

-- be advantageous. Obviously,

should not exceed the volatilization temperature the temperature oithe material undergoing treatment, nor should it be so high as to decompose the oil or fatty acid.

But within these operative limits suitabl'e temperatures can be chosen.

We have listed many .catalysts which can be used. Any amine hydroiodide is operative and such a class includes all oi the aliphatic amine hydroiodides and the aromatic amine hydroiodldes. Ammonium iodide is one of the amine hydroiodides which can be used.

All of the alkyl primary amine hydroiodides,

, such agthe hydroiodides oi butyl, hexyl, octyl,

decyl, 'dodecyl, octadecenyl and octadecylamine may be used, as well as secondary amine hydroiodides, such as the hydroiodides of dibutyl. didodecyl and dioctyiamines. Any of the aryl amine hydroiodides, such as thehydroiodides of aniline, 'diethylaniline, toluidineand naphthylaminesmay be used. Tertiary amine hydroiodides are operative catalysts for our process.

Diethylanlline hydroiodicle has been specifically referred to infcertain 'of the above examples. Other tertiary amines are tributylamine hydroiodide, and any other aromatic, aliphatic, or mixed aromatic-aliphatic amine hydroiodide. Bubstitutedorsanic amine hydroiodides suchas ,triethanolamine hydroiodide, diamino diethyl ether hydroiodides, keto octadecyl amine hydroiodide 0r amino acid hydroiodides are further examples of compounds which can be used.

Having thus described our invention, what we claim as new and desire to secure by Letters Patentis:

1. The-process oi conjugating a polyene comthe heating after substantial conjugation has been effected, but before the polyen'ecompound I pound chosen from the group consisting of unconjugated polyene fats and fatty acids which comprises heating said polyene compound in the presence oi! an iodide chosen from the group conof ammonium iodide, aliphatic amine hydroiodides and aromatic amine hydroiodides, and discontinuing the heating after substantial conjugation has been eflected, but before the thus conjugated polyene compound becomes substantially heat-bodied.

2. The process as in claim 1 wherein the poiyene compound is soy bean oil.

. 3. The process as in claim 1 wherein the polyene compound is linseed 011'.

4. The process as in claim 1 wherein the polyene compound is heated at a temperature of about 200 C.-to 300 C. in the presence of the iodide.

5. The process of conjugating a polyene compound chosen fromthe group consisting of unconjugated polyene fats andfatty acids which comprises heating said polyene compound in the presence of ammonium iodide, and discontinuing becomes substantially heat bodied.

6. The process ofconjugating a polyene compound chosen from the group consisting of un- 

